BMR Calculator
Determine your Basal Metabolic Rate (BMR). Find out how much energy your body expends at complete rest just to keep you alive.
Mathematical Overview
Mifflin-St Jeor Equation
Introduced in 1990, this equation is currently the most predictive and accurate formula for estimating resting metabolism.
W = weight in kg, H = height in cm, A = age in years.
Revised Harris-Benedict Equation
Originally created in 1919 and revised by Roza and Shizgal in 1984, this remains a widely used clinical fallback.
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Frequently Asked Questions
What exactly is BMR?
Basal Metabolic Rate (BMR) is the total number of calories your body needs to perform basic, life-sustaining functions (like breathing, circulating blood, and cell production) while at complete rest.
Mifflin-St Jeor vs. Harris-Benedict: Which is better?
The Mifflin-St Jeor equation, introduced in 1990, is considered the most accurate standard for modern lifestyles by the American Dietetic Association. The original Harris-Benedict equation (1919) tends to overestimate calorie needs by about 5%.
How do I use my BMR to lose weight?
Your BMR is your baseline. To find your total daily energy expenditure (TDEE), you multiply your BMR by an activity factor. To lose weight, you must consume fewer calories than your TDEE (creating a calorie deficit).
Does muscle mass affect BMR?
Yes. Muscle tissue burns more calories at rest than fat tissue. Standard BMR formulas use total body weight, so they may slightly underestimate the BMR of highly muscular athletes and overestimate it for those with high body fat percentages.